Don't persist and sync omnibox extension keywords.

chrome/browser/resources/options/search_engine_manager_engine_list.js

Index: chrome/browser/resources/options/search_engine_manager_engine_list.js
diff --git a/chrome/browser/resources/options/search_engine_manager_engine_list.js b/chrome/browser/resources/options/search_engine_manager_engine_list.js
index 2076f26b920899268f59b3763e01085081ea7994..f94a01bb16085df17e6c3d21714cba63af46a230 100644
--- a/chrome/browser/resources/options/search_engine_manager_engine_list.js
+++ b/chrome/browser/resources/options/search_engine_manager_engine_list.js
@@ -10,7 +10,7 @@
  *            displayName: string,
  *            extension: (Object|undefined),
  *            iconURL: (string|undefined),
- *            isExtension: boolean,
+ *            isOmniboxExtension: boolean,
  *            keyword: string,
  *            modelIndex: string,
  *            name: string,
@@ -141,7 +141,7 @@ cr.define('options.search_engines', function() {
       // And the URL column.
       var urlEl = this.createEditableTextCell(engine.url);
       // Extensions should not display a URL column.
-      if (!engine.isExtension) {
+      if (!engine.isOmniboxExtension) {
         var urlWithButtonEl = this.ownerDocument.createElement('div');
         urlWithButtonEl.appendChild(urlEl);
         urlWithButtonEl.className = 'url-column';
@@ -181,9 +181,6 @@ cr.define('options.search_engines', function() {
       if (engine.urlLocked)
         this.urlField_.disabled = true;
 
-      if (engine.isExtension)
-        this.nameField_.disabled = true;

[Dan Beam, 2014/10/28 01:36:59]

can omnibox extensions be renamed?

[vasilii, 2014/10/28 14:01:38]

No. But this case is handled below. engine.canBeEdited is false.

-
       if (this.isPlaceholder) {
         this.nameField_.placeholder =
             loadTimeData.getString('searchEngineTableNamePlaceholder');